Repetition, as they say, is a sign you failed to get your message across the first time.

That certainly appeared to be true at Prime Minister's Questions (PMQs) yesterday.

David Cameron spent much of the half-hour session attempting to wrestle with a rather convoluted metaphor, designed, it appeared, to cast Labour as responsible for ruining the UK economy.

Unfortunately for the Prime Minister, he struggled to get his point across, again and again and- you get the point.

The Conservative leader had started off well, with a flourish even, as he accused Ed Miliband of being the "croupier in the casino" as the UK economy went bust.

But his comment caused heads to be scratched even on the Tory benches. The Labour leader has been accused of many things, but never of looking like he knows anything about gambling.

One MP even questioned afterwards whether the public would believe that Mr Miliband had ever visited a casino.

His charge having failed to stick the first time, the PM came back for a second go. This time he widened his attack, suggesting that the whole of the previous Labour government had been croupiers.

But he appeared to lose it on the third reference, when he suggested that Ed and his team had merely been "sitting in the casino" when disaster struck – conjuring up an image of confused customers.

By the fourth time- well, even some Tory backbenchers looked weary. For that matter, the metaphor itself was a bit confused.

Are croupiers really the bad guys in a casino? There is a reason, surely, that the phrase is not "the croupier always wins".

Still it may get more traction than the PM's other rebranding attempt of the day.

He told the opposition leader that the "bedroom tax" was not the "bedroom tax". It was the "single room supplement".

Political observers suggested this had about as much chance of catching on as the "community charge" had for the "poll tax".